I've gotton the white tiger download to breed with the bengal tiger download, but it required modding the files first. You have to modify two files from both species you want to breed and it is not as easy as it looks. I am not done fully testing it yet, but the offspring seems to always take after the female, regardless of what the code says.
To give an idea of the difficultity, the first time I tried it, they interbred, but all my african adventure stuff disappeared.